1. Field of the invention
The invention relates to a multifunction excitation voltage regulator for an alternator for charging the battery of an automobile vehicle.
2. Description of the prior art
At present excitation voltage regulators for alternators for charging the battery of an automobile vehicle can be divided into two major families, so-called single-function regulators and so-called multifunction regulators, as shown in FIGS. 1a through 1d which relate to the prior art.
As shown in FIGS. 1a and 1b in the case of single-function regulators an indicator lamp LT is connected in series with the ignition switch K and with the field coil In. A half-wave rectifier comprising a trio T of low-power diodes is connected between the phase windings of the alternator ALT and the terminal of the indicator lamp LT that is not connected to the ignition switch K. In normal operation the rectified voltage from the trio of diodes turns off the indicator lamp LT. If the alternator is not running, for example because its drive belt has broken or because the engine of the vehicle is stopped, the indicator lamp LT is turned on and carries a current of between 200 and 300 mA when the ignition switch is closed, the alternator being then in a pre-excitation condition rather than the excitation condition enabling the battery B to be charged.
When the alternator ALT starts and reaches a speed in the region of 1,000 revolutions per minute it "cuts in", changing from the pre-excitation condition created by the indicator lamp LT to the excitation condition created by the alternator ALT and the trio T. The alternator cuts in when the voltage between the phase windings of the alternator is above 1.2 volts. Thus in the case of single-function regulators rotation of the alternator is sensed by the trio T, the indicator lamp LT providing the pre-excitation condition of the field coil In. The terminal EXC of the regulator REG supplies the regulated current in the form of rectangular pulses with a variable cyclic ratio energizing the field coil In. The alternator voltage reference for the regulator is taken from the terminal D+ of the trio T, for example.
The single-function regulator is so called because there is only one way to detect a voltage fault between phases of the alternator by means of the indicator lamp LT and the trio T and no way to detect battery charging voltage regulation faults such as a battery overvoltage or an open-circuit excitation winding, for example.
In multifunction regulators, on the other hand, as shown in FIGS. 1c and 1d the trio T is eliminated and the indicator lamp LT is connected to the regulator REG itself and serves as the single fault indicator. Rotation of the alternator ALT is sensed by an additional connecting wire which connects the regulator REG to one phase winding of the alternator ALT and delivers to the regulator an "alternator phase present" signal PA.
The indicator lamp LT can then indicate other faults such as a battery overvoltage if, for example, the field coil In is permanently excited because of a short-circuit in the switching device controlled by the regulator REG which normally delivers regulated current pulses to the field coil.
Also, a further connecting wire F senses closure of the ignition switch even if the indicator lamp LT should fail. The wire F is installed during manufacture of the vehicle and it has the disadvantage of non-negligible manufacturing cost since it is relatively long as it connects the dashboard of the vehicle to the alternator or the regulator REG.
It should further be noted that in both single-function and multifunction regulators of a conventional kind there is no total integration onto one and the same substrate, a printed circuit being used to interconnect the various semiconductor components of the regulator.
An object of the present invention is to provide a regulator having the characteristics of single-function regulators combined with those of multifunction regulators; accordingly, this type of regulator is referred to hereinafter as a plurifunction regulator.
In addition to the notable feature just mentioned, the regulator in accordance with the invention is intended to remove the risk of full-field excitation of the field coil of the alternator.
Another object of the present invention is a regulator with the signalling device or indicator lamp protected against an auxiliary external supply with a voltage very much higher than the nominal voltage of the alternator being applied to the regulator (this is especially valuable in countries with a northern or continental climate).
Another object of the present invention is a regulator which makes it possible to magnetize automatically the magnetic circuits of the alternator even if the battery is absent.
Another object of the present invention is a regulator in which the sensitivity of the alternator phase voltage input to spurious signals is reduced.
Another object of the present invention is a regulator in which the risk of excitation of the field coil when the alternator is stopped due to the polarization of the stator to a positive potential is eliminated.
Another object of the present invention is a regulator in which the alternator phase voltage filtering system does not increase the amplitude of the alternator phase voltage when the rotation speed of the alternator increases during regulation of the phase voltage.
Another object of the present invention is a regulator whereby discharge of the battery is indicated notwithstanding the existence of a high-amplitude alternator phase voltage created by strong remanence of the magnetic circuit of the alternator.
Another object of the present invention is a regulator in which the response time of the combination of the regulator and the alternator during regulation of the alternator phase voltage is substantially inversely proportional to the rotation speed of the alternator in order to allow for significant variations in the amplitude of the alternator phase voltage during phase voltage regulation at high alternator rotation speeds.